Westerbeke 20.0 BEDA Operator's Manual page 29

DC ELECTRICAL SYSTEM/ALTERNATOR
E. Now check the voltage between the alternator output
terminal (B+) and ground. If the circuit is good, the
voltage at the alternator should be the same as the bat-
tery, or if an isolator is in the circuit the alternator volt-
age will be zero. If not, a problem exists in the circuit
between the alternator and the battery. Check all con-
nections - look for an opening in the charging circuit.
TESTING THE STARTING
BAnERY-ALTERNATOR
(ENGINE RUNNING)
M ULTIMETER
ITCH,
-
L
miD
0
COM
/
t'L
,ENGIN E
~ROUND
F. Start the engine again. Check the voltage between the
alternator output and ground.
The voltage reading for a properly operating alternator
should be between 13.5 and 14.5 volts. If your alterna-
tor is over- or undercharging, have it repaired at a reli-
able service shop.
NOTE: Bejore removing the alternator for repair, use your
voltmeter to ensure that 12 vofts DC excitation is present
at the EXC terminal if the previous test showed only bat-
tery voltage at the B output terminaL
If 12 volts is not present at the EXC terminal trace the
wiring, look for breaks and poor connections.
Alternator is Working
4. Check the voltage of the service battery. This battery
should have a voltage between 13 and 14 volts when the
engine is running. If not, there is a problem in the service
battery charging circuit. Trouble-shoot the service battery
charging circuit by checking the wiring and connections,
the solenoid, isolator, battery switch and the battery itself.
am
. MULTIMETER
0
COM
- SERVICE'
JIATT~IW.
TESTING THE SERVICE
BAnERY (ENGINE RUNNING)
...
A
CAUTION:
When pfidorm/ng
tests
on the alterna·
tor charging cln:ult do not use a high voltage testsr (le
Megger}. You can damage the alternator diodes.
Engines & Generators ·
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